Hey guys just wanted to make a talk-shitpost. To update about my situation.
I posted two days ago asking about the legality of the events of my first day of work.
To recap, I am allergic to fabric softener and wasn't able to wash the shirt beforehand. I wasn't told that the shirt was mandatory and there was no mention of it in the dress code they asked me to sign. I ended up putting the shirt on once I was asked to do so and was still sent home.
It turns out that she was not supposed to do that. Trainees are not expected to wear the work shirt during the training period. I quit over this and overall how I was treated that day (because fuck going to work and dealing with that). I hope that everyone who was throwing salt on me in the comments learns from this. It's not ok to treat people like that, and there is no shame in standing up for yourself. It may not be illegal what she did, but she definitely cost the company the money it took to pay me and the value an able bodied, hardworking man would have provided over the long term.
I'll be contacting HR tomorrow and launching a counter offensive on her job.